GENEVA — Following China’s recent charge that Washington was breaking global commerce rules, the World Trade Organization launched a formal investigation on July 31 of the U.S. ban on Chinese poultry, according to The Associated Press. Washington had imposed "naked discriminative protectionism measures" in completely banning Chinese chicken products entering the U.S. market, Beijing told the W.T.O.'s dispute settlement body.

The U.S. claims it is still examining the safety of Chinese poultry for human consumption.

This marks China's second W.T.O. request to establish an investigative panel. The U.S. prevented China's first request last month, but under W.T.O. rules it cannot block this request again. As a result, a panel has been set up to deliver a ruling at some point next year, the trade body confirmed.

This poultry controversy has been percolating for five years. In 2004, both China and the U.S. banned each other's poultry following an outbreak of avian influenza in Asia. China lifted the ban after several months, but it complained Washington would not do the same. Since then, China has imported more than 4 million tons of U.S. poultry — mostly feet and other parts of birds popular in China.

"The U.S. has completely banned the importation of poultry products from China since 2007 through its annual appropriation acts and other related measures," China said in a statement. "These unilateral measures fundamentally violate relevant W.T.O. rules, significantly impede the ordinary Sino-U.S. trade in poultry products, and substantially impair the rights and benefits that Chinese enterprises deserve to enjoy. These measures are naked discriminative protectionism measures, which are strongly opposed by the Chinese government and enterprises."

Beijing is also protesting a measure in the 2009 U.S. federal spending bill, signed by President Barack Obama in March, that extends the U.S. ban by blocking any funds from being used to facilitate imports of poultry products from China. The U.S. denied the ban was discriminatory or protectionist, and said its authorities were "continuing to work together to reach an objective, science-based response" to China's request for equal treatment of its poultry exports.